The invention relates to an apparatus for charging a processing line with printed sheets, envelopes or similar printed products (hereinafter collectively referred to as printed sheets), wherein the processing line comprises a conveying rotor which pulls off the printed sheets individually from a stack stored in an adjacent printed sheet magazine and against which a printed sheet can be moved on an approximately circular orbit via a gripped edge, with the printed sheet first having been partially lifted off from the stack by means of a separating apparatus. The conveying rotor is provided with at least one multiple-part gripper arrangement controllable into an open or closed position which takes over the printed sheet from the separating apparatus.
An apparatus of this type, often referred to as a feeder, is described and illustrated in Swiss patent document CH-A-641 112. In this known arrangement, the separating apparatus which is configured as a plurality of suction devices, partially lifts off the individual printed sheets from the bottom side of the stack around a pivot axis of the separating apparatus prior to being gripped by the rotating grippers. From this position, the individual printed sheets are gripped by the passing gripper arrangement of the conveying rotor, with a trailing gripper arm of the gripper arrangement moving behind the lifted-off printed sheet in a supporting manner and the leading gripper arm snapping back from an open position of the gripper arrangement toward the trailing gripper arm into a closed position.
During this process, the trailing gripper arm is set to project beyond the perimeter of the conveying rotor and the leading gripper arm is returned to the perimeter of the conveying rotor so that a collision with the printed sheet that was lifted off the stack cannot occur. The printed sheet that is gripped by the gripper arrangement is then pulled forward by way of a force action from under the stack on the pivot shaft of the separating apparatus which bends the printed sheet. The printed sheets may get damaged because of the resulting friction, particularly on the surface that faces the pivot shaft.
Furthermore, the gripper arrangement generates clamping marks that are left on the printed sheets because of the relative movements of the latter with respect to the gripper arrangement.